July 26, 2007
James Hansen Fears Runaway Ice Sheet Melting
Space scientist James Hansen, head of NASA's Goddard Institute for Space Studies, fears a runaway glacier melting scenario where sea levels will rise 5 meters.
The current rate of sea level change is not without consequences. However, the primary issue is whether global warming will reach a level such that ice sheets begin to disintegrate in a rapid, non-linear fashion on West Antarctica, Greenland or both. Once well under way, such a collapse might be impossible to stop, because there are multiple positive feedbacks. In that event, a sea level rise of several metres at least would be expected.
As an example, let us say that ice sheet melting adds 1 centimetre to sea level for the decade 2005 to 2015, and that this doubles each decade until the West Antarctic ice sheet is largely depleted. This would yield a rise in sea level of more than 5 metres by 2095.
Of course, I cannot prove that my choice of a 10-year doubling time is accurate but I'd bet $1000 to a doughnut that it provides a far better estimate of the ice sheet's contribution to sea level rise than a linear response. In my opinion, if the world warms by 2 °C to 3 °C, such massive sea level rise is inevitable, and a substantial fraction of the rise would occur within a century. Business-as-usual global warming would almost surely send the planet beyond a tipping point, guaranteeing a disastrous degree of sea level rise.
I see this outcome as unlikely for a few reasons:
- We will run out of fossil fuels before we can increase atmospheric carbon dioxide up to levels where we could cause a massive melting. Global warming models of future CO2 emissions are unrealistic because they take the OPEC official oil and natural gas reserves at face value.
- We will find much cheaper ways to produce non-fossil fuels energy sources and this will make fossil fuels much less appealing. People will find it easier to reject fossil fuels when the cost in living standards and lifestyles goes down due to technological advances. Growing opposition to coal electric plants illustrates where public attitudes are headed.
- We will be able to cheaply engineer the climate to reverse a big warming. We could cool the planet for $100 million per year.
I'm not worried about global warming. I am worried about Peak Oil. Our future must be driven by electric power (and we can generate that electric with nukes, solar panels or wind turbines). But we aren't far enough along in the development of the batteries we need to replace most liquid fuel used in transportation. The transition period off of fossil fuels could therefore feature some really deep wrenching global recessions as economies reorder to deal with declining oil production. At the risk of boring long time readers, batteries are the key technology of our energy future.
Update: For more on climate engineering see here and here and here.
"This would yield a rise in sea level of more than 5 metres by 2095."
Much of the concern for global warming seems to be based on inaccurate projections that assume that technology will stand still for the next hundred years.
It's not clear to me that we have enough of the necessary metals to make enough high power high energy density batteries to replace fossil fuels. Look at global lithium reserves. Ditto cobalt. Immense numbers of batteries also have their own environmental problems.
Personal rapid transit powered by nukes seems to me to be probably the way to go in the long term.
In the shorter term, hybrids are far from the only technology available that could improve the efficiency of our current type of cars. Better aerodynamics and more efficient engines, better materials, and hybrid tech should enable us to get 80 mpg or so. Combine that with simply kicking the SUVs etc off the street via taxation or licensing and you have a fairly sustainable system.
It's not clear to me that we have enough of the necessary metals to make enough high power high energy density batteries to replace fossil fuels. Look at global lithium reserves. Ditto cobalt.
The oceans contain about 200 billion tons of lithium (at .15 ppm). This will undoubtedly be more expensive to extract than current sources, but lithium is only a small part of the mass of a Li-ion battery. Cobalt is not necessary as an electrode material for these batteries; the new generation of Li cells being brought to the market now avoid it and use nanocrystalline titanium dioxide or iron phosphate (or other such potentially cheaper materials) instead.
It's also not clear why you'd want to use lithium for stationary batteries, where specific energy is not the main concern.
Whenever anyone talks about shortages of particular metals/minerals, I have to put on my rocket ranger hat and note that floating around the Earth are treasure troves of just about every element of importance to an industrialized society. Not only are asteroids rich in these resources, but once a reasonable infrastructure is developed they should actually be easier and cheaper to extract from asteroids than they are from the ground. It's gravity that makes deep-earth mining so difficult and dangerous.
Granted, it won't be trivial to develop zero-gee mining and processing techniques, but that's just a matter of trial-and-error, and the rewards will be enormous. Developing versatile space infrastructure will make solutions to many of our problems easier to implement, and is something I would hope we'd have well begun, considering the time-frame under discussion here.
Personal rapid transit sounds a LOT less difficult to develop than asteroid mining. Also a lot more incrementally possible.
Does anyone here know why aluminum isn't the preferred electron receiver for batteries? Possibly with iron donating? Maybe with Sulfur even?
Likewise, what's the status of Sodium Sulfur battery development? What are the barriers?
We will quickly reach a point where 80 mpg, with existing oil field depletion, increasing demand and producers keeping more of their production for their own uses, or the doubling, tripling or more of our miles per gallon makes little difference. A different transportation method, like all electric, is all that will spare us on the down side of Peak Oil.
It looks like lead-acid will work just fine, if needed. Check out Firefly batteries.
Batteries are more than good enough for PHEV40's, which would eliminate 90% of gas usage.
The perfect is the enemy of the good.